Circuitry adapted to perform data processing,combination and alarm operations in reception in the operating-reserve system of isofrequency connections with middle and long-range radio relays



Dec. 30. 1969 sARATl 3,487,309

CIRCUITRY ADAPTED TO PERFORM DATA PROCESSING, COMBINATION AND ALARMOPERATIONS IN RECEPTION IN THE OPERATING-RESERVE SYSTEM OF ISOFREQUENCYCONNECTIONS WITH MIDDLE AND LONG-RANGE RADIO RELAYS Filed March 14, 19665 Sheets-Sheet 1 X t 2 I S Q Q w E k I Q Lu v- N 0 a t m L N U U Q Q A1A 2 RF v A'2 A'1 Q TRA.

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INVENTOR L u/ 8419/! 7'/ ATTORNEYS 1.. SARATI 3,487,309

COMBINATION AND OF ISOFREQUENCY CONNECTIONS WITH MIDDLE AND LONG-RANGERADIO RELAYS 5 Sheets-Sheet 2 R w M M N at m M a M5 w W to: S m C NA 2623% was 3 1 Ill. I 3 an A v \U llll 2: I E :Q

CIRCUITRY ADAPTED TO PERFORM DATA PROCESSING, ALARM OPERATIONS INRECEPTION IN THE OPERATING-RESERVE SYSTEM Dec. 30. 1969 Filed March 14,1966 Q to MQQ2 NQME ATTORNEYS Dec. 30. 1969 L. SARATI 3,487,309

CIRCUITRY ADAPTED TO PERFORM DATA PROCESSING, COMBINATION AND ALARM.OPERATIONS IN RECEPTION IN THE OPERATING-RESERVE SYSTEM OF ISOFREQUENCYCONNECTIONS WITH MIDDLE AND LONG-RANGE RADIO RELAYS Filed March 14, 19663 Sheets-$heet 3 "'G'V V:

INVENTOR A u/@/ $4 EA 7'/ BY ;(m7 74% ATTORNEYS United States Patent US.Cl. 3252 7 Claims ABSTRACT OF THE DISCLOSURE The disclosure relates toan alarm circuit wherein a pair of receivers is provided, each forreceiving a signal from a transmitter, each receiver providing signalsfor a summing circuit and also providing fault signals to an alarmsignal producing means, the alarm signal producing means operating inaccordance with preset logic conditions to disconnect said receiversfrom said summing circuit, said alarm signal producing means alsoproviding a signal to said transmitter to provide an indication at thetransmitter after a fault has existed for a predetermined time.

This invention relates to telephone and television-communications bymiddle and long-range radio relays, and in particular, to circuitryadapted to perform data processing, operating-reserve combination andalarm operations in the final receiving stations of such connections.

For a better understanding of the accomplishments that are attained bythe present invention, reference will be made to the practice that isusually followed in the radio-relay technique. A twofold number ofpermanently switched-on receivers is provided in the final receivingstations of a radio relay, whereby, when a fault occurs in the operatingreceiver, the reserve receiver is directly substituted for the faultyone. In some cases, the neces sity to have the number of carrierfrequencies, as utilized in radio stations, restricted within givenlimits, did suggest the utilization of radio-links of so-calledoperatingreserve type, having an isofrequency reserve, i.e., ofconnections wherein the reserve radio-relay is operated at a carrierfrequency similar to that of the currently operated radio relay.

The expensive solution of having a spatial difference connection wasdiscarded for obvious economic reasons, whereby it became necessary toconsider which combination procedure would allow the utilization of theisofrequency reserve under the best conditions of reliability.

An object of this invention is to provide circuitry in which bothreceivers are connected with the antenna, and their outputs areconnected with a device adapted to linearly combine the two incomingsignals, and possibly to shut out one of them, while keeping the levelof output signal unchanged in any case (as well known, the linearcombination allows the attainment of a signal-noise ratio which is 3 dbbetter than the signal-noise ratio of the components, when theassumption is made that both component noises have a similar intensity,and are incoherent with each other can be considered as a sound one);moreover, said receivers are to be supervised in such a manner as toprevent information having a signal-noise ratio lower than apro-established limit value from being fed to the summer.

Another object of the present invention is to provide circuitry adaptedto perform combination and alarm operations on the receiving side, inthe operating-reserve ice type of isofrequency radio-links, wherein theinputs of both receivers are permanently connected with the antenna,while the outputs thereof are both connected, under normal conditions,with a utilization device through an adding or combining device whereinthe linear combination of the inputs is performed, and alarm informationis respectively fed by either receiver to a data processor whenever thelevel of pilot tone that is coupled with the transit information dropsbelow a pre-established level and further alarm information is given outby the same receivers whenever the signal-noise ratio of the transitinformation drops below a pre-established value and the first-mentionedalarm information is utilized in the data processor to give the outputinformations according to transducer functions, wherein certain outputinformations are designed to control the combiner, summer or addingdevice circuit for disconnecting the receivers from the utilizationdevice while the other output information is designed to be utilized asan alarm criterion in the receiving station of radio-link, wherefrom thealarm is forwarded to the transmitting station for signalling and/ orlocating possible faults.

Further objects and advantages of the invention will be betterappreciated from a consideration of the following description of apreferred embodiment thereof, taken with the accompanying drawings, bothdescription and drawings given as a nonlimiting example only.

'In the drawings:

FIG. 1 is a connection diagram of the circuitry according to theinvention.

FIG. 2 is an embodiment of data processor (E as shown in FIG. 1.

FIG. 3 is an embodiment of adding device 2, as shown in FIG. 1.

As shown in the block diagram of FIG. 1, the inputs of receivers RC andRC; are connected by means of a hybrid circuit Rf, with the antennatransformer A while their outputs are connected with the utilizationdevice M through a linear combiner or adding device 2. By such method,both receivers are normally utilized simultaneously. The block E is anelectronic data processing unit, and the alarm informations P P R R thatare given out by control devices embodied in the receivers R and R arefed thereto. In fact, each receiver is controlled by two devices whichrespectively take knowledge of the noise level that comes with thetransit information and of the pilot tone that is introduced in thetransmission to control the continuity of connection.

In case of faulty service, the alarm informations P P R R are fed, bythe above devices, to the receiving data processor E thereby triggeringit according to a preestablished program. In fact, said data processorprovides, if required, for having the summing device 2 operated in sucha manner as to disconnect the faulty receiver RC or RC In addition tothe above-described operations, the receiving data processor E, alsoprovides for determining the particular condition which occurs when thealarm condition persists in both receivers RC and RC for more than apreestablished time limit. Such condition is usually indicative of afault in the transmitting station since it is not likely that 'bothreceivers RC and RC are faulty. When the transmitting station T is ofthe operating-reserve type and thus equipped with control and switchingdevices adapted to detect possible faults in the operating transmitterand accordingly to have the transmission switched over onto the reservetransmitter, the persistence of alarm conditions simultaneously in RCand RC for more than the pre-established time limits is indicative of anonintervention of the protection devices in transmitter T. Saidcondition is thus made known by means of the transmission of signal A tothe transmitting station T. In FIG. 1, TRA is the transmission unit bywhich the signal A is transmitted; A and A respectively are thetransformers of receiving antenna and of transmitting antenna, and RICis the receiving unit. See US. Patent No. 3,421,145 for furtherdescription of T and RIC. The signal A is simultaneously fed also to thereceiving section of the radio-link.

The degree of reliability of operating-reserve connections can beimproved by the use of the above-stated protections, since, due to theaction thereof, possible breaks might occur only when heavy faults wouldsimultaneously take place in both transmitters or in both receivers.

As previously stated, two kinds of informations P and R coming from thecontrol devices as embodied in both receivers RC RC are utilized by theelectronic data processor E Said two alarm informations are indicativeof the hereinafter stated conditions:

R =Increase in the noise that comes with the useful information when apre-established limit value is exceeded (such information can beobtained by means of an express noise detector having a well-definedband width, or by referring to AGC-voltage of the IF amplifier. Thealarm information is forwarded to data processor E e.g., when the noiseresults in a signal-noise ratio smaller than 30 db. at the output ofreceiver).

P =Decrease, over a given-pre-established value (e.g. 6 db.) in thelevel of received pilot tone. As stated previously, the summing device 2is controlled, when receiving, by the data processor E, in such a manneras to attain the best utilization of signals coming from both receiversRC and RC This can be obtained when the hereinafter stated conditionsare maintained:

(1) When both receivers RC and RC are in proper working conditions, thesignals present at their outputs can be linearly added with one another.In fact, in such a case, since the connection is of the isofrequencytype, the signal-noise ratio present at the output of summing device 2,is 3 db. higher than that of the component signals.

(2) When one of receivers RC and RC is faulty,

the transit from its output and the summing device 2 shall bediscontinued. At the same time, the output of 2 is to be shortcircuitedonto the output of the other receiver.

(3) When an alarm condition is simultaneously detected on both receiversRC and RC due to an excess of noise R R then the connections betweenboth receiver outputs and the summing circuit are to be both broken, toprevent too high noises from reaching the utilization device M The aboveconditions can be maintained by the circuitry as diagrammatically shownin FIG. 3, and wherein the summing device 2 circuitry is clearly setforth in detail. As can be readily appreciated from a consideration ofsaid circuit diagram, the outputs K and K of the hepta-pole Er shall beactivated, when the transit from the output RH or RH to the resistiveadder, consisting of the resistances R R and R is to be discontinued. Bythe activation of either outputs K K the related relay S or S isenergized, whereby their contacts S S or S S are switched over, thuscutting the receiver RC or RC which is under alarm conditions, out ofthe utilizer device, and shortcuiting at the same time the resistiveadder.

Let us consider now the operation of data processor E,. In respect ofthe four incoming information signals, the logical operation ofreceiving data processor can be summarized by the following relations:

When both receivers RC and RC are faulty, the general alarm informationis present on the output A However, such information is forwarded onlywhen the simultaneous faulty condition of said two receivers lasts overa given time limit '1'.

The above-stated relations can be obtained by means of the logicalcircuit as shown in FIG. 2. As it can be noticed therefrom, recourse isto be made to seven NOR- circuits, three AND-circuits and one monostablemultivibrator MS for the realization of said logical circuit. Themonostable multivibrator MS is utilized to provide the alarm signal A,only after a time delay '1.

Three examples of faulty conditions which can occur in the radioconnection are quoted hereinafter, to better explain the operation ofdata processor E EXAMPLE 1 Assuming the pilot receiver pertaining to thefirst radio receiver RC to be under alarm conditions, in such a case,the input P of NOR1 is switched from the zero state, over to the onestate and consequently its output will be switched from the one state,over to the zero state. The information coming from receiver RC issimultaneously forwarded to AND1 circuit, both inputs of which will be,in such a case, in the one state. In fact, no alarm signal has beenforwarded from the second receiver RC whereby the output of NOR4,connected with the second input of AND1 is still in the one state. Sinceboth inputs of AND1 are now in the one state, the output thereof will bealso in the one state, and consequently the output of NOR2 is switchedfrom the one state over the zero state. Since the output of NOR2 isconnected to NOR3, it follows that the output of said N'OR3 is switchedfrom the zero state to the one state which results in giving an order toisolate the output of the first receiver RC from the summing device.

Considering now which may be the operating condition wherein a responseof alarm device D is obtained, under normal conditions the outputs ofNOR1 and NOR4, that are connected with both inputs of NOR7 are in theone state whereby the output of NOR7 is in the zero state. When thefirst receiver became faulty, the input P is changed from the zero stateto the one state and consequently also the output of NOR1 was moved fromthe one state to the zero state. Since no changes have occurred in thestate of NOR4 output, no variations can take place in the output ofNOR7, whereby the alarm device D cannot give any response.

EXAMPLE 2 The behavior of the data processor E when both radio receiversare under alarm conditions, is considered in this second example. Withregard to signals P and P only, assuming that both inputs P and P aretransmitted from the zero state to the one state, in such a case, bothoutputs of NOR1 and NOR4 are converted from the one state to the zerostate. As conseqeucnes of such condition, the hereinafter-statedsituation follows:

(a) The signs of inputs of the circuits AND1 and AND2 are opposite toeach other; in fact, when considering e.g. the circuit AND1, the firstinput (which is directly connected with the input P is in the one statewhile the second input (which is connected with the output of NOR4) isin the zero state. Under such condition, the output of AND1 will stay inthe zero state and thus no change occurs in the state of output Kwhereby no switching-over order is given. Similarly, no change occurs inthe output K (b) The two inputs of NOR7-that are respectively connectedwith the outputs of NOR1 and NOR4are both in the zero state and thus theoutput thereof is transmitted from the zero state to the one state. Suchchange in the state results in an excitation of monostable multivibratorMSl which after its characteristic relaxation time 1-, that is set on avalue greater than the time required for the switching over oftransmitting section, provides for changing its output (that isconnected with the first input of AND3) from the zero state to the onestate. Should in the meantime the transmitting section be switched over,whereby the alarm informations P and P have come back in their normalconditions, then also the output of NOR7 will have come back to zerostate, while if no change has occurred in the state of inputs P and Pthe output of NOR7 also stays in the one state. Now, since latter outputis also connected with the second input of AND3, the output thereof isconverted from the zero state to the one state, thus giving the alarmcondition A Obviously, such alarm condition stays as long as the outputsof NORl and NOR4 are kept in the zero state.

EXAMPLE 3 The behavior of data processor, when an alarm condition R or Roccurs, due to an increase over a given limit value, in the noise thatgoes with the useful information, will be considered in this example.

In such a case, which results in a change from the zero state to the onestate of the inputs R or R since the latter inputs are respectivelyconnected with the first input of NORZ, and with the second input ofNORS, it follows that the inputs of following NOR3 and NOR6 shall bechanged whenever and R or R alarm condition is detected in the relatedreceiver. And since a change in the state of respective outputs of NORZand of NORS results in a change in the state of NOR3 and respectively ofNOR6, it follows that the controls K and/ or K are always brought intoaction as a consequence of the presence of related alarms R and/or RShould two noise alarms simultaneously occur, then the behavior of alarmdevice D would be similar to that as stated in Example 2 as well as inExample 3 for K and K Though the invention has been described withrespect to a preferred embodiment thereof, many variations andmodifications thereof will immediately become apparent to those skilledin the art. It is therefore the intention that the appended claims beinterpreted as broadly as possible in view of the prior art to includeall such vatriations and modifications.

Having described my invention, I claim:

1. An alarm circuit for use in operation-reserve systems of isofrequencyradio connections comprising, in combination, receiving means includingfirst and second receivers for receiving transmitted signals from atransmitter means, output means connected to receive outputs from saidfirst and second receivers, each of said receivers including first meansfor providing first fault signals P and P from said first and secondreceivers respectively in response to a first fault condition and secondmeans for providing second fault signals R and R from said first andsecond receivers respectively in response to a second fault condition,alarm signal producing means connected to receive said fault signals P PR and R said alarm signal producing means operating to provide an outputsignal K upon receipt thereby of either a fault signal P in the'absenceof a fault signal P and fault signal R or a fault signal R and an outputsignal K upon receipt thereby of either a fault signal P in the absenceof a fault signal P and fault signal R or, a fault signal R and alarmsignal responsive means connected to receive signals K and K said alarmsignal responsive means operating in response to signal K, to disconnectsaid first receiver from said output means and in response to signal Kto disconnect said second receiver from said output means.

2. The alarm circuit as set forth in claim 1 wherein said receivingmeans includes an antenna system, having a single antenna, said firstand second receivers being normally operative in the absence of saidfirst and second fault signals to concurrently receive signals from saidsingle antenna and provide output signals to said output means, saidoutput means operating to combine said output signals. I 1

3. The alarm circuit as set forth in claim 1 wherein said alarm signalproducing means operates in response to concurrent receipt thereby for apredetermined time of either fault signals P and P or R and R to providean output signal A,, said alarm circuit including transmitting meansoperative in response to said output signal A 4. An alarm circuit as setforth in claim 1 wherein said alarm signal producing means includes afirst NOR circuit responsive to said P and R fault signals, a fourth NORcircuit responsive to said R and P fault signals, a first AND circuitresponsive to said P signal and the output of said fourth NOR circuit, asecond NOR circuit responsive to said R signal and the output of saidfirst AND circuit, a third NOR circuit responsive to the output of saidsecond NOR circuit to provide said K signal, a second AND circuitresponsive to said P signal and the output of said first NOR circuit, afifth NOR circuit responsive to said R signal and the output of saidsecond AND circuit and a sixth NOR circuit responsive to the output ofsaid fifth NOR circuit for providing said K signal.

5. An alarm circuit as set forth in claim 3 wherein said alarm signalproducing means includes a first NOR circuit responsive to said P and Rfault signals, a fourth NOR circuit responsive to said R and P faultsignals, a first AND circuit responsive to said P signal and the outputof said fourth NOR circuit, a second NOR circuit responsive to said Rsignal and the output of said first AND circuit, a third NOR circuitresponsive to the output of said second NOR circuit to provide said Ksignal, a second" AND circuit responsive to said P signal and the outputof said first NOR circuit, a fifth NOR circuit responsive to said Rsignal and the output of said second AND circuit and a sixth NOR circuitresponsive to the output of said fifth NOR circuit for providing said Ksignal.

6. An alarm circuit as set forth in claim 4 further including a seventhNOR circuit responsive to the output of said first and said fourth NORcircuits, means responsive to a predetermined output from said seventhNOR circuit for providing an output signal, said last-mentioned meansproviding said signal after a predetermined time delay and a third ANDcircuit responsive to the output of said seventh NOR circuit and saidthird AND circuit to provide said A signal.

7. An alarm circuit as set forth in claim 5 further including a seventhNOR circuit responsive to the output of said first and said fourth NORcircuits, means responsive to. a predetermined output from said seventhNOR circuit for providing an output signalysaid last-mentioned meansproviding said signal after a predetermined time delay and a 'third ANDcircuit responsive to the output of said seventh NOR circuit and saidthird AND circuit to provide said A signal.

References Cited UNITED STATES PATENTS 2,892,930 6/1959 Magnuski et al32556 2,947,861 8/1960 Ulstad et al. 325--305 3,003,031 10/1961Posthumus 178-69 3,048,840 8/1962 Ferrar et a1 343l00 3,204,204 8/1965Buxton et a1. 178-69 X 3,296,532 1/1967 Robinson 325-305 ROBERT L.GRIFFIN, Primary Examiner BENEDICT V. SAFOUREK, Assistant Examiner US.Cl. X.R.

